A forage harvester usually is equipped with a detachable crop collecting apparatus, such as a row crop attachment or a pick-up device, which takes the crop off the field and feeds it to the inlet of the front unit of the forage harvester. In order to obtain good chopping quality, i.e. comminution of the crop material to a constant chop length, an even mat of crop material has to be fed at a constant speed towards the cutterhead to be comminuted between the rotating knives of the cutterhead and a stationary shearbar. The chopped material is led to a blower unit with paddles, which throw it up into a discharge spout for collection in a cart or container.
In order to accomplish such constant flow, the crop material is compressed between upper and lower feeder means which have portions lying adjacent the shearbar. This compact construction of the feeder means and the cutterhead hinders access thereto for inspection, cleaning and service operations.
Access to the shearbar and the cutterhead may be required for inspection and adjustment of the shearbar to knife clearance and for replacement of the shearbar or the cutterhead knives.
Access for cleaning and service may be required between the feeder means, which usually comprise sets of feeder rolls. To prevent damage of the cutterhead knives, the feeder means may be equipped with a detector, which is operable to immediately stop the feeder means upon detection of a foreign object. Such detector usually is installed within the front roll of the lower feeder means. Easy servicing and/or replacement of this detector is essential, because of the delicacy of its electronic components. Therefore good accessability to the front roll is required.
The blower unit is mounted between the main frame of the forage harvester and the front unit. Access for cleaning, inspection and/or adjustment of the blower paddles involves splitting between the front unit and the main frame. Currently the whole front unit has to be removed for servicing of the blower, which implies the use of additional hoist equipment such as a tackle or a lift truck. Consequently such operation cannot take place in the field.
U.S. Pat. No. 4,938,425, issued Jul. 3, 1990 in the name of Terry A. Williams, et al, discloses a front unit which comprises a cutterhead frame, supporting a cutterhead and a shearbar, and a feeder section, supporting upper and lower feed rolls. For ready access to the shearbar and the cutterhead knives the feeder section can be swung about a vertical axis. Cleaning of the feeder section is cumbersome. Any crop material between the upper and lower feed rolls remains compressed therebetween by the spring loaded upper feed rolls. Also, no means are provided for providing direct access and easy removal of the front lower feed roll, which remains secluded below the upper front feed roll.
Another feed roll arrangement is shown in U.S. Pat. No. 3,985,306, issued Oct. 12, 1976 in the name of Robert A. Wagstaff, et al. Access to the shearbar can be gained by pivoting the rear feed roll relative to the front feed roll to a service position above the front feed roll. Thereby accessability to the lower feed roll is not improved, as it also remains hidden below the upper feed roll.
Neither of aforementioned documents shows means for easy access between the cutterhead and the blower unit.
These prior art documents do not deal in a satisfactory way with the problems of easy access between the upper and lower means, between the cutterhead and the blower and to the lower feed roll.
Therefore it is an object of the present invention to provide a front unit which comprises a cutterhead portion and feeder portions which are movable relative to one another to improve accessibility therebetween and to the components thereof for inspection, cleaning, adjustment and service operations.